JP7219285B2 - In-plane magnetic film, multilayer structure of in-plane magnetic film, hard bias layer, magnetoresistive element, and sputtering target - Google Patents

Description

The present invention relates to an in-plane magnetized film, an in-plane magnetized film multilayer structure, a hard bias layer, a magnetoresistive effect element, and a sputtering target, and more specifically, to a coercive force Hc of 2.00 kOe or more and a CoPt that can realize the magnetic performance of remanent magnetization Mrt of 2.00 memu/cm ² or more without performing film formation by heating the substrate (hereinafter sometimes referred to as thermal film formation). - In-plane magnetization film of oxide system, CoPt-oxide system in-plane magnetization film multilayer structure and hard bias layer, and said CoPt-oxide system in-plane magnetization film, said CoPt-oxide system in-plane magnetization film The present invention relates to a magnetoresistive element and a sputtering target related to a magnetic film multilayer structure or the hard bias layer. The CoPt-oxide-based in-plane magnetization film and the CoPt-oxide-based in-plane magnetization film multilayer structure can be used for a hard bias layer of a magnetoresistive effect element.

If the hard bias layer has a coercive force Hc of 2.00 kOe or more and a residual magnetization Mrt per unit area of 2.00 memu/cm ² or more, compared with the hard bias layer of the current magnetoresistive effect element, It is considered that they have coercive force and remanent magnetization of equal or higher degree. In the present application, the hard bias layer is a thin film magnet that applies a bias magnetic field to a magnetic layer exhibiting a magnetoresistive effect (hereinafter sometimes referred to as a free magnetic layer).

Magnetic sensors are currently used in many fields, and one of the widely used magnetic sensors is a magnetoresistive element.

A magnetoresistive element has a magnetic layer (free magnetic layer) that exerts a magnetoresistive effect, and a hard bias layer that applies a bias magnetic field to the magnetic layer (free magnetic layer). It is required that a magnetic field of a predetermined magnitude or more can be stably applied to the free magnetic layer.

Therefore, the hard bias layer is required to have high coercive force and high residual magnetization.

However, the coercive force of the hard bias layer of the current magnetoresistive effect element is about 2 kOe (for example, FIG. 7 of Patent Document 1), and realization of a higher coercive force is desired.

Further, it is desired that the residual magnetization per unit area is approximately 2 memu/cm ² or more (eg, paragraph 0007 of Patent Document 2).

As a technique that may be able to cope with these, there is a technique described in Patent Document 3, for example. The technique described in Patent Document 3 is a seed layer (Ta layer) provided between a sensor laminate (laminate having a free magnetic layer) and a hard bias layer, and a face-centered Ta layer formed on the Ta layer. A composite seed layer (including a metal layer having a cubic (111) crystal structure or a hexagonal close-packed (001) crystal structure) orients the magnetic material so that the easy axis is oriented in the longitudinal direction, thereby increasing the coercivity of the hard bias layer. This is a method that attempts to improve However, it does not satisfy the magnetic properties desired for the hard bias layer. Also, in this method, it is necessary to increase the thickness of the seed layer provided between the sensor laminate and the hard bias layer in order to improve the coercive force. Therefore, the structure also has a problem that the applied magnetic field to the free magnetic layer in the sensor laminate is weakened.

Further, Patent Document 4 describes the use of FePt as a magnetic material for the hard bias layer, the FePt hard bias layer having a Pt or Fe seed layer, and the Pt or Fe capping layer. 4 proposes a structure in which the Pt or Fe in the seed and capping layers and the FePt in the hard bias layer intermingle during annealing, where the annealing temperature is about 250-350°C. . However, in the heating process required for forming this hard bias layer, it is necessary to consider the influence on other films already laminated, and this heating process should be avoided as much as possible.

In Patent Document 5, the annealing temperature is optimized, it is shown that the annealing temperature can be lowered to about 200° C., and the coercive force of the hard bias layer is 3.5 kOe or more. However, the residual magnetization per unit area is about 1.2 memu/cm ² , which does not satisfy the magnetic properties desired for the hard bias layer.

Patent Document 6 describes a magnetic recording medium for longitudinal recording, in which the magnetic layer includes ferromagnetic crystal grains having a hexagonal close-packed structure and non-magnetic grains mainly composed of oxide surrounding them. However, there is no example of using such a granular structure for the hard bias layer of a magnetoresistive effect element. The technique described in Patent Document 6 aims at reducing the signal-to-noise ratio, which is a problem of magnetic recording media, and multi-layers magnetic layers by using non-magnetic layers between magnetic layers. The upper and lower magnetic layers have antiferromagnetic coupling, and the structure is not suitable for improving the coercive force of the magnetic layers.

JP 2008-283016 A Japanese translation of PCT publication No. 2008-547150 JP 2011-008907 A U.S. Patent Application Publication No. 2009/027493A1 JP 2012-216275 A JP-A-2003-178423

When considering application to an actual magnetoresistive effect element, it is preferable to make the sensor laminate (laminate including the free magnetic layer) and the hard bias layer as thin as possible, and do not perform thermal film formation. is preferred.

In order to obtain a hard bias layer that exceeds the coercive force (approximately 2 kOe) and residual magnetization per unit area (approximately 2 memu/cm ² ) of the hard bias layer of the current magnetoresistive effect element while satisfying this condition, The present inventor believes that it is necessary to search for elements and compounds that are different from the elements and compounds that are currently used in hard bias layers. The present inventor thought that it was promising. The present inventor also thought that it would be promising to multilayer the CoPt-based in-plane magnetization film using an oxide using a non-magnetic intermediate layer.

The present invention has been made in view of this point, and the magnetic performance that the coercive force Hc is 2.00 kOe or more and the remanent magnetization Mrt per unit area is 2.00 memu/cm ² or more is An object of the present invention is to provide an in-plane magnetization film, an in-plane magnetization film multilayer structure, and a hard bias layer that can be achieved without thermal film formation, and the in-plane magnetization film and the in-plane magnetization film multilayer structure. A complementary object is to provide a magnetoresistive element and a sputtering target associated with the structure or said hard bias layer.

The present invention solves the above problems by the following in-plane magnetization film, in-plane magnetization multilayer structure, hard bias layer, magnetoresistive element, and sputtering target.

That is, the in-plane magnetization film according to the present invention is an in-plane magnetization film used as a hard bias layer of a magnetoresistive effect element, containing metal Co, metal Pt and an oxide. 55 at % or more and less than 95 at % of metal Co, more than 5 at % and 45 at % or less of metal Pt, and 10 vol % of the oxide with respect to the entire in-plane magnetization film. 42 vol % or less, and a thickness of 20 nm or more and 80 nm or less.

In the present application, a hard bias layer is a thin film magnet that applies a bias magnetic field to a free magnetic layer exhibiting a magnetoresistive effect.

Further, in the present application, "residual magnetization per unit area" of the in-plane magnetization film is a value obtained by multiplying the remanent magnetization per unit volume of the in-plane magnetization film by the thickness of the in-plane magnetization film. be.

The in-plane magnetization film may have a granular structure composed of CoPt alloy crystal grains and crystal grain boundaries of the oxide.

Here, the grain boundary is a boundary between crystal grains.

The oxide may contain at least one of oxides of Ti, Si, W, B, Mo, Ta, and Nb.

A first aspect of the in-plane magnetization film multilayer structure according to the present invention is an in-plane magnetization film multilayer structure used as a hard bias layer of a magnetoresistive effect element, comprising a plurality of in-plane magnetization films and a non-magnetic intermediate layer. and wherein the non-magnetic intermediate layer is arranged between the in-plane magnetized films, and the in-plane magnetized films adjacent to each other with the non-magnetic intermediate layer interposed therebetween are ferromagnetic. The in-plane magnetization film contains metal Co, metal Pt, and an oxide, and the content of metal Co is 55 at % or more and less than 95 at % with respect to the total metal components of the in-plane magnetization film. contains more than 5 at % and 45 at % or less of metal Pt, and contains 10 vol % or more and 42 vol % or less of the oxide with respect to the entire in-plane magnetization film, and the in-plane magnetization film multilayer structure is The in-plane magnetic film multilayer structure is characterized by having a coercive force of 2.00 kOe or more and a residual magnetization of 2.00 memu/cm ² or more per unit area.

Here, in the present application, a non-magnetic intermediate layer is a non-magnetic layer arranged between in-plane magnetic films.

In the present application, ferromagnetic coupling means an exchange interaction that works when the spins of adjacent magnetic layers (here, the in-plane magnetized films) with a non-magnetic intermediate layer interposed therebetween are parallel (in the same direction). It is a combination based on

In addition, in the present application, "residual magnetization per unit area" of the in-plane magnetization film multilayer structure means that the remanent magnetization per unit volume of the in-plane magnetization film included in the in-plane magnetization film multilayer structure It is a value obtained by multiplying the total thickness of the in-plane magnetization films included in the film multilayer structure.

A second aspect of the in-plane magnetization film multilayer structure according to the present invention is an in-plane magnetization film multilayer structure used as a hard bias layer of a magnetoresistive effect element, comprising a plurality of in-plane magnetization films and a hexagonal crystal structure. and a non-magnetic intermediate layer having a close-packed structure, wherein the non-magnetic intermediate layer is arranged between the in-plane magnetized films and is adjacent to each other with the non-magnetic intermediate layer interposed therebetween. The in-plane magnetized films that match each other are ferromagnetically coupled to each other, and the in-plane magnetized films contain metal Co, metal Pt and oxides, and the total metal component of the in-plane magnetized films is , containing 55 at % or more and less than 95 at % of metallic Co, containing more than 5 at % and 45 at % or less of metallic Pt, and containing 10 vol % or more and 42 vol % or less of the oxide with respect to the entire in-plane magnetic film. 1. The in-plane magnetization film multilayer structure, wherein the total thickness of the plurality of in-plane magnetization films is 20 nm or more.

The non-magnetic intermediate layer is preferably made of Ru or Ru alloy.

In the in-plane magnetization film multilayer structure, the in-plane magnetization film may have a granular structure composed of CoPt alloy crystal grains and crystal grain boundaries of the oxide.

In the in-plane magnetization film multilayer structure, the oxide may include at least one of oxides of Ti, Si, W, B, Mo, Ta, and Nb.

A hard bias layer according to the present invention is a hard bias layer characterized by having the in-plane magnetization film or the in-plane magnetization film multilayer structure.

A magnetoresistive element according to the present invention is a magnetoresistive element comprising the hard bias layer.

A sputtering target according to the present invention is a sputtering target used for forming an in-plane magnetized film, which is used as at least a part of a hard bias layer of a magnetoresistive element, at room temperature, and comprises metallic Co, metallic Pt and an oxide containing 60 at% or more and less than 95 at% of metal Co and more than 5 at% and 40 at% or less of metal Pt, based on the total metal components of the sputtering target, and the entire sputtering target contains On the other hand, the in-plane magnetization film formed by containing 10 vol % or more and 40 vol % or less of the oxide has a coercive force of 2.00 kOe or more and a residual magnetization per unit area of 2.00 memu/cm ² or more. A sputtering target characterized by:

Here, room temperature film formation means film formation without heating the substrate.

According to the present invention, the magnetic performance of coercive force Hc of 2.00 kOe or more and remanent magnetization Mrt per unit area of 2.00 memu/cm ² or more is realized without thermal film formation. In-plane magnetization films, in-plane magnetization multilayer structures and hard bias layers can be provided.

FIG. 2 is a cross-sectional view schematically showing a state in which a CoPt-oxide-based in-plane magnetization film 10 according to the first embodiment of the present invention is applied to a hard bias layer 14 of a magnetoresistive effect element 12; FIG. 5 is a cross-sectional view schematically showing a state in which an in-plane magnetization film multilayer structure 20 according to a second embodiment of the present invention is applied to a hard bias layer 26 of a magnetoresistive effect element 24; FIG. 2 is a perspective view schematically showing the shape of a sliced sample 80 after performing a slice processing. An example of an observed image obtained by imaging using a scanning transmission electron microscope (observed image of Example 45). Results of line analysis (elemental analysis) performed in the thickness direction of the in-plane magnetized film of Example 45 (along the black line in FIG. 4).

(1) First Embodiment FIG. 1 is a cross-sectional view schematically showing a state in which an in-plane magnetization film 10 according to a first embodiment of the present invention is applied to a hard bias layer 14 of a magnetoresistance effect element 12. is. In FIG. 1, illustration of an underlayer (the in-plane magnetization film 10 is formed on the underlayer) is omitted.

Here, the configuration shown in FIG. 1 will be described with a tunneling magnetoresistance effect element as the magnetoresistance effect element 12 in mind. The application is not limited to the hard bias layer of an element, and application to the hard bias layer of, for example, a giant magnetoresistive element or an anisotropic magnetoresistive element is also possible.

The magnetoresistive element 12 (here, tunneling magnetoresistive element) is composed of two ferromagnetic layers (free magnetic layer 16, pin layer 52). The pinned layer 52 has its magnetization direction fixed, for example, by being fixed by exchange coupling with an adjacent antiferromagnetic layer (not shown). The magnetization direction of the free magnetic layer 16 can be freely rotated with respect to the magnetization direction of the pinned layer 52 in the presence of an external magnetic field. When the free magnetic layer 16 rotates with respect to the magnetization direction of the pinned layer 52 due to an external magnetic field, the electrical resistance changes, so the external magnetic field can be detected by detecting the change in electrical resistance.

The hard bias layer 14 has a role of applying a bias magnetic field to the free magnetic layer 16 and stabilizing the magnetization direction axis of the free magnetic layer 16 . The insulating layer 50 is made of an electrically insulating material, and the sensor current flowing vertically through the sensor laminate (the free magnetic layer 16, the barrier layer 54, and the pinned layer 52) causes the sensor laminate (the free magnetic layer 16, The barrier layer 54 and the pinned layer 52) have a role of suppressing shunting to the hard bias layers 14 on both sides.

As shown in FIG. 1, the in-plane magnetized film 10 according to the first embodiment can be used as the hard bias layer 14 of the magnetoresistive effect element 12, and the bias magnetic field applied to the free magnetic layer 16 exhibiting the magnetoresistive effect. can be added. The hard bias layer 14 is composed only of the in-plane magnetization film 10 according to the first embodiment, and is composed of a single layer of the in-plane magnetization film 10 .

The in-plane magnetized film 10 according to the first embodiment contains an oxide and has a coercive force equal to or higher than that of the hard bias layer of the current magnetoresistive effect element (a coercive force of 2.00 kOe or more). ) and residual magnetization per unit area (2.00 memu/cm ² or more). Specifically, the in-plane magnetization film 10 according to the first embodiment is a CoPt-oxide-based in-plane magnetization film containing metal Co, metal Pt, and an oxide. 55 at % or more and less than 95 at % of metal Co and more than 5 at % and 45 at % or less of metal Pt are contained with respect to the total metal components of the film, and 10 vol of the oxide is contained with respect to the entire in-plane magnetization film. % or more and 42 vol % or less, and the thickness is 20 nm or more and 80 nm or less.

In the present application, the metal Co may be simply described as Co, the metal Pt may be simply described as Pt, and the metal Ru may be simply described as Ru. Other metal elements may also be described in the same way.

(1-1) Components of In-plane Magnetization Film 10 As described above, the in-plane magnetization film 10 according to the first embodiment contains Co and Pt as metal components, and also contains oxides.

Metallic Co and metallic Pt are constituent components of magnetic crystal grains (micromagnets) in an in-plane magnetized film formed by sputtering.

Co is a ferromagnetic metal element and plays a central role in the formation of magnetic crystal grains (micromagnets) in the in-plane magnetic film. The viewpoint of increasing the magnetocrystalline anisotropy constant Ku of the CoPt alloy crystal grains (magnetic crystal grains) in the in-plane magnetization film obtained by sputtering and the CoPt alloy crystal grains (magnetic crystal grains) in the obtained in-plane magnetization film From the viewpoint of maintaining the magnetism, the content of Co in the in-plane magnetization film according to this embodiment is set to 55 at % or more and less than 95 at % with respect to the total metal components in the in-plane magnetization film. From the same point of view, the content of Co in the in-plane magnetized film according to the present embodiment is preferably 55 at % or more and 80 at % or less with respect to the total metal components in the in-plane magnetized film. It is more preferably 65 at % or more and 75 at % or less.

Pt has the function of reducing the magnetic moment of the alloy by being alloyed with Co within a predetermined composition range, and has the role of adjusting the magnetic strength of the magnetic crystal grains. On the other hand, it has the function of increasing the magnetocrystalline anisotropy constant Ku of the CoPt alloy crystal grains (magnetic crystal grains) in the in-plane magnetization film obtained by sputtering, thereby increasing the coercive force of the in-plane magnetization film. From the viewpoint of increasing the coercive force of the in-plane magnetization film and from the viewpoint of adjusting the magnetism of the CoPt alloy crystal grains (magnetic crystal grains) in the obtained in-plane magnetization film, The content of Pt is more than 5 at % and 45 at % or less with respect to the total metal components in the in-plane magnetization film. From the same point of view, the content of Pt in the in-plane magnetized film according to the present embodiment is preferably 20 at % or more and 40 at % or less with respect to the total metal components in the in-plane magnetized film. It is more preferably 25 at % or more and 35 at % or less.

The oxide contained in the in-plane magnetic film 10 according to the first embodiment includes at least one of oxides of Ti, Si, W, B, Mo, Ta, and Nb. In the in-plane magnetization film 10, the CoPt alloy magnetic crystal grains are separated from each other by the non-magnetic material made of oxide as described above to form a granular structure. That is, this granular structure consists of CoPt alloy crystal grains and the oxide crystal grain boundaries surrounding them.

Therefore, it is preferable to increase the content of the oxide in the in-plane magnetization film 10, because it becomes easier to separate the magnetic crystal grains reliably and to make the magnetic crystal grains more independent. From this point of view, the content of the oxide contained in the in-plane magnetized film 10 according to the first embodiment is set to 10 vol % or more. The content of the oxide contained in the magnetic film 10 is preferably 12.5 vol % or more, more preferably 15 vol % or more.

However, if the content of oxides in the in-plane magnetization film 10 becomes too large, the oxides will mix into the CoPt alloy crystal grains (magnetic crystal grains) and affect the crystallinity of the CoPt alloy crystal grains (magnetic crystal grains). This may adversely affect the ratio of structures other than hcp in CoPt alloy crystal grains (magnetic crystal grains). From this point of view, the content of the oxide contained in the in-plane magnetized film 10 according to the first embodiment is set to 42 vol % or less. The content of the oxide contained in the magnetic film 10 is preferably 37.5 vol % or less, more preferably 35 vol % or less.

Therefore, in the first embodiment, the content of oxide contained in the in-plane magnetized film 10 is set to 10 vol % or more and 42 vol % or less, and the in-plane magnetized film 10 according to the first embodiment The content of the oxide contained therein is preferably 12.5 vol % or more and 37.5 vol % or less, more preferably 15 vol % or more and 35 vol % or less.

As will be demonstrated in Examples described later, if WO ₃ or MoO ₃ is contained as an oxide, the coercive force Hc of the in-plane magnetized film 10 increases, so WO ₃ or MoO ₃ can be contained as an oxide. preferable.

In the current in-plane magnetization film, as a grain boundary material that partitions CoPt alloy crystal grains (magnetic crystal grains), simple elements such as Cr, W, Ta, and B are used. To some extent, it is considered to form a solid solution in the CoPt alloy. For this reason, it is considered that the CoPt alloy crystal grains (magnetic crystal grains) of the current in-plane magnetization film are adversely affected by the crystallinity and have reduced saturation magnetization and residual magnetization. It is believed that its coercivity Hc and remanent magnetization values are adversely affected.

On the other hand, in the in-plane magnetized film 10 according to the first embodiment, since the grain boundary material is an oxide, the grain boundary The material hardly dissolves in the CoPt alloy. Therefore, the saturation magnetization and residual magnetization of the CoPt alloy crystal grains (magnetic crystal grains) in the in-plane magnetization film 10 according to the first embodiment are increased, and the in-plane magnetization film 10 according to the first embodiment coercive force Hc and remanent magnetization of . This is demonstrated in Examples described later.

(1-2) Thickness of In-plane Magnetization Film 10 As demonstrated in Examples described later, the thickness of the CoPt—WO ₃ in-plane magnetization film (in the case of a single layer without a non-magnetic intermediate layer) is When it is less than 20 nm, the residual magnetization Mrt per unit area becomes less than 2.00 memu/cm ² (Comparative Example 7), and the thickness of the CoPt—WO ₃ in-plane magnetization film (in the case of a single layer without a non-magnetic intermediate layer) ) exceeds 80 nm, the coercive force Hc falls below 2.00 kOe ₍ comparative examples 8 and 9). is set to 20 nm or more and 80 nm or less.

However, as demonstrated in Examples described later, when the thickness of the single-layer CoPt-WO3 in _- plane magnetic film is 20 to 40 nm, the coercive force Hc increases (Examples 9, 12, 13). When the thickness is 20 to 30 nm, the coercive force Hc becomes particularly large (Examples 9 and 12). It is more preferable to have

(1-3) Coercive force and residual magnetization of the in-plane magnetized film 10 The in-plane magnetized film 10 according to the first embodiment has a coercive force that is equal to or greater than that of the hard bias layer of the current magnetoresistive effect element. It is a single-layer in-plane magnetic film having a coercive force (coercive force of 2.00 kOe or more) and remanent magnetization per unit area (2.00 memu/cm ² or more) of the same degree or more.

As will be described in detail in a second embodiment to be described later, the in-plane magnetization film 10 according to the first embodiment is multi-layered with a non-magnetic intermediate layer 22 (see FIG. 2) interposed therebetween to reduce the residual magnetization. The coercive force can be further improved while maintaining the value. This is demonstrated in Examples described later.

(1-4) Underlayer The underlayer used for forming the in-plane magnetized film 10 according to the first embodiment has the same crystal structure (hexagonal maximum Underlayers of metal Ru or Ru alloys with a close-packed structure hcp) are suitable.

In order to orderly orient the magnetic crystal grains (CoPt alloy grains) of the laminated in-plane magnetic film (CoPt-oxide) 10, the surface of the Ru underlayer or Ru alloy underlayer used has (10.0) plane Alternatively, it is preferable to arrange many (11.0) planes.

The underlayer used for forming the in-plane magnetized film according to the present invention is not limited to the Ru underlayer or the Ru alloy underlayer. Any underlayer can be used as long as it can be oriented and can promote magnetic separation between CoPt magnetic crystal grains.

(1-5) Sputtering Target The sputtering target used in fabricating the in-plane magnetization film 10 according to the first embodiment is an in-plane magnetization film used as at least part of the hard bias layer 14 of the magnetoresistive effect element 12. 10 by room-temperature film formation, containing metallic Co, metallic Pt, and an oxide, and containing 60 at% or more of metallic Co and 95 at% of the total metal components of the sputtering target. %, contains more than 5 at % and 40 at % or less of metal Pt, and contains 10 vol % or more and 40 vol % or less of the oxide with respect to the entire sputtering target, and the formed in-plane magnetized film has a coercive force of It is 2.00 kOe or more, and the residual magnetization per unit area is 2.00 memu/cm ² or more. As described later in "(J) Composition analysis of manufactured CoPt-oxide-based in-plane magnetized film", the actual composition of the manufactured CoPt-oxide-based in-plane magnetized film (by composition analysis, (obtained composition) and the composition of the sputtering target used for the production of the CoPt-oxide-based in-plane magnetization film. It is a composition range set in consideration, and does not match the composition range of each element contained in the in-plane magnetization film 10 according to the first embodiment.

The constituent components (metallic Co, metallic Pt, and oxide) of this sputtering target are described in conjunction with the constituent components of the in-plane magnetized film described in the above "(1-1) Constituent Components of In-plane Magnetized Film 10". , so the description is omitted.

(1-6) Method for forming the in-plane magnetized film 10 The in-plane magnetized film 10 according to the first embodiment is formed by sputtering using the sputtering target described in "(1-5) Sputtering target". It is formed by forming a film on a predetermined base film (the base film described in the above “(1-4) Base film”). It should be noted that heating is not required in this film formation process, and the in-plane magnetization film 10 according to the first embodiment can be formed by film formation at room temperature.

(2) Second Embodiment FIG. 2 schematically shows a state in which an in-plane magnetization film multilayer structure 20 according to a second embodiment of the present invention is applied to a hard bias layer 26 of a magnetoresistance effect element 24. It is a sectional view.

The in-plane magnetization film multilayer structure 20 according to the second embodiment will be described below. Since the underlying film used in this case, the sputtering target used in fabricating the in-plane magnetized film 10, and the method of forming the in-plane magnetized film 10 have already been described in "(1) First Embodiment", Description is omitted.

As shown in FIG. 2, the in-plane magnetization film multilayer structure 20 according to the second embodiment of the present invention includes a plurality of in-plane magnetization films 10 according to the first embodiment, and the plurality of in-plane magnetization films 10 according to the first embodiment. A non-magnetic intermediate layer 22 is provided between the in-plane magnetized films 10 , and the structure is such that a plurality of in-plane magnetized films 10 are stacked with the non-magnetic intermediate layers 22 interposed therebetween.

In the in-plane magnetization film multilayer structure 20, the thickness of each layer of the in-plane magnetization film 10 is typically 5 nm or more and 30 nm or less. In addition, the total thickness (total thickness) of the in-plane magnetization film 10 is set to 20 nm or more from the viewpoint of making the residual magnetization Mrt 2 meum/cm ² or more. Regarding the upper limit of the total thickness (total thickness) of the in-plane magnetized film 10, as will be described later, the adjacent in-plane magnetized films 10 separated by the interposition of the non-magnetic intermediate layer 22 are ferromagnetic. Since coupling is performed, even if the total thickness (total thickness) of the in-plane magnetized film 10 increases, the coercive force Hc does not decrease theoretically and there is no upper limit. In fact, it has been confirmed by the examples described later that the coercive force Hc is 2 kOe or more up to at least the total thickness (total thickness) of 100 nm. The thickness of each layer of the in-plane magnetization film 10 in the in-plane magnetization film multilayer structure 20 is preferably 5 nm or more and 15 nm or less, and preferably 10 nm or more and 15 nm or less, from the viewpoint of further increasing the coercive force Hc. It is more preferable to have

The in-plane magnetic film multilayer structure 20 according to the second embodiment can be used as the hard bias layer 26 of the magnetoresistive effect element 24, and can apply a bias magnetic field to the free magnetic layer 28 that exhibits the magnetoresistive effect. .

The non-magnetic intermediate layer 22 is interposed between the in-plane magnetized films 10 according to the first embodiment, and has a role of separating the in-plane magnetized films 10 and multilayering the in-plane magnetized films 10 . By multilayering the in-plane magnetized film 10 with the non-magnetic intermediate layer 22 interposed, the coercive force Hc can be further improved while maintaining the value of the remanent magnetization Mrt.

The adjacent in-plane magnetized films 10 separated by the interposition of the non-magnetic intermediate layer 22 are arranged such that their spins are parallel (in the same direction). By arranging in this manner, the adjacent in-plane magnetized films 10 separated by the interposition of the non-magnetic intermediate layer 22 are ferromagnetically coupled to each other. The coercive force Hc can be further improved while maintaining the same.

Therefore, the in-plane magnetic film multilayer structure 20 according to the second embodiment can exhibit a good coercive force Hc.

The metal used for the non-magnetic intermediate layer 22 should have the same crystal structure (hexagonal close-packed structure hcp) as the CoPt alloy magnetic crystal grains, from the viewpoint of not damaging the crystal structure of the CoPt alloy magnetic crystal grains. Specifically, the nonmagnetic intermediate layer 22 is preferably made of metal Ru or a Ru alloy having the same crystal structure (hexagonal close-packed structure hcp) as the crystal structure of the CoPt alloy magnetic crystal grains in the in-plane magnetic film 10. can be used.

When the metal used for the non-magnetic intermediate layer 22 is a Ru alloy, specific examples of additive elements that can be used include Cr, Pt, and Co. It is preferable to set the range in which the close-packed structure hcp is obtained.

A bulk sample of Ru alloy was produced by arc melting, and X-ray diffraction peak analysis was performed using an X-ray diffraction device (XRD: (SmartLab manufactured by Rigaku Corporation). is 50 at %, a mixed phase of the hexagonal close-packed structure hcp and RuCr ₂ was confirmed. Therefore, when a RuCr alloy is used for the non-magnetic intermediate layer 22, the amount of Cr added should be less than 50 at %. It is preferably less than 40 at%, more preferably less than 30 at%.In addition, in the RuPt alloy, when the amount of Pt added is 15 at%, the hexagonal close-packed structure hcp and the plane derived from Pt Since mixed phases with a centered cubic structure fcc were confirmed, when a RuPt alloy is used for the non-magnetic intermediate layer 22, the amount of Pt to be added is appropriately less than 15 atomic percent, preferably less than 12.5 atomic percent. In addition, the RuCo alloy forms a hexagonal close-packed structure hcp regardless of the amount of Co added, but when Co is added to 40 at% or more, it becomes a magnetic material. is suitably less than 40 atomic %, preferably less than 30 atomic %, and more preferably less than 20 atomic %.

Also, the thickness of the non-magnetic intermediate layer 22 is preferably 0.3 nm or more and 3 nm or less. As demonstrated in Examples described later, the coercive force Hc of the in-plane magnetic film 10 can be reduced by about 15% by using a non-magnetic intermediate layer made of metal Ru or a Ru alloy and having a thickness of 0.3 nm or more and 3 nm or less. can be improved. However, if the non-magnetic intermediate layer has a thickness of 0.3 nm or more and 3 nm or less, the effect of improving the coercive force Hc of the in-plane magnetized film 10 is almost the same. From the viewpoint of ease of application (a thinner thickness makes it easier to apply to a magnetoresistive effect element), the thickness of the non-magnetic intermediate layer 22 is more preferably 0.3 nm or more and 1.5 nm or less. , 0.3 nm or more and 0.6 nm or less are particularly preferable.

Examples and comparative examples for supporting the present invention will be described below with respect to CoPt-oxide-based in-plane magnetic films. In the following (A), the composition ratio of Co and Pt, which are the metal components of the CoPt-oxide system in-plane magnetization film, is studied, and in the following (B), the CoPt-oxide system in-plane magnetization The volume ratio of the oxide (WO ₃ ) in the film is studied. In the following (C), the thickness of the in-plane magnetic film of the CoPt-oxide system is studied, and in the following (D), The type of oxide for the CoPt-oxide-based in-plane magnetic film is being studied. In addition, (E) to (I) below describe multi-layering of a CoPt-oxide-based in-plane magnetic film using a non-magnetic intermediate layer.

In addition, in the following (J), the actual composition (composition obtained by composition analysis) of the CoPt-oxide-based in-plane magnetization film manufactured and the composition of the CoPt-oxide-based in-plane magnetization film In order to confirm the degree of deviation from the composition of the sputtering target used, the in-plane magnetic films of CoPt--WO ₃ system of Examples 45, 47, 50 and 52 were picked up and subjected to composition analysis. As a result, it was found that there was a difference between the composition of the in-plane magnetization film and the composition of the sputtering target used to produce the in-plane magnetization film. Therefore, the compositions of the CoPt-oxide-based in-plane magnetic films other than those of Examples 45, 47, 50, and 52 for which the composition analysis was actually performed were clarified from the composition analysis results of Examples 45, 47, 50, and 52. The composition of the CoPt-oxide-based in-plane magnetization film in each example was calculated from the composition of the sputtering target used in the production in consideration of the compositional deviation.

<(A) Examination of the composition ratio of Co and Pt, which are the metal components of the CoPt-oxide-based in-plane magnetic film (Examples 1 to 7, Comparative examples 1 and 2)>
Experimental data was obtained by changing the composition of Co and Pt, which are the metal components of the CoPt-oxide in-plane magnetic film formed on the Ru underlayer. The CoPt-oxide-based in-plane magnetic film to be formed is a single layer, and no non-magnetic intermediate layer is provided. Specifically, it is as follows.

On a Si substrate, a Ru underlayer was formed to a thickness of 30 nm by sputtering using ES-3100W manufactured by Eiko Engineering Co., Ltd., and a CoPt-oxide in-plane magnetic film was formed thereon by the same apparatus. was formed to a thickness of 50 nm by a sputtering method. In this film forming process, the substrate was not heated, and the film was formed at room temperature. The sputtering apparatus used for sputtering in the examples and comparative examples of the present application is ES-3100W manufactured by Eiko Engineering Co., Ltd., but the name of the apparatus is omitted below.

The content of Pt with respect to the sum of Co and Pt, which are the metal components of the CoPt-oxide-based in-plane magnetic film to be formed, was varied from 5.7 at % to 50.5 at % in steps of 5.6 at %, and samples were prepared. data was obtained.

The hysteresis loop of the produced CoPt-oxide-based in-plane magnetized film was measured by a vibration magnetometer (VSM: TM-VSM211483-HGC manufactured by Tamagawa Seisakusho Co., Ltd.) (hereinafter referred to as a vibration magnetometer). . Coercive force Hc (kOe) and residual magnetization Mr (memu/cm ³ ) were read from the measured hysteresis loop. Then, the read remanent magnetization Mr (memu/cm ³ ) was multiplied by the film thickness of 50 nm of the manufactured CoPt-oxide system in-plane magnetization film, and the unit area of the manufactured CoPt-oxide system in-plane magnetization film was obtained. Permanent magnetization Mrt (memu/cm ² ) was calculated. The results are shown in Table 1 below.

As can be seen from Table 1, the content of Pt with respect to the total metal components (Co, Pt) of the CoPt-oxide-based in-plane magnetization film is 10 to 45 at%, and the entire CoPt-oxide-based in-plane magnetization film The volume ratio of the oxide (WO ₃ ) to the oxide (WO 3 ) is 31.0 vol% and the thickness is 50 nm. In addition, the magnetic performance that the remanent magnetization Mrt per unit area is 2.00 memu/cm ² or more is realized by film formation at room temperature without heating the substrate.

On the other hand, the content of Pt with respect to the total of the metal components (Co, Pt) of the CoPt-oxide-based in-plane magnetic film is 5.7 at %, and Comparative Example 1, which is not included in the scope of the present invention, has a coercive force Hc is 1.47 kOe and coercive force Hc is less than 2.00 kOe. Further, the content of Pt with respect to the total of the metal components (Co, Pt) of the CoPt-oxide-based in-plane magnetic film is 50.5 at%, and Comparative Example 2, which is not included in the scope of the present invention, has a unit area The remanent magnetization Mrt per unit area is 1.62 memu/cm ² and the remanent magnetization Mrt per unit area is less than 2.00 memu/cm ² .

<(B) Examination of volume ratio of oxide (WO ₃ ) in in-plane magnetic film of CoPt-oxide system (Examples 8 to 11, Comparative examples 3 to 6)>
Experimental data was obtained by changing the volume ratio of the oxide (WO ₃ ) in the CoPt-oxide in-plane magnetic film formed on the Ru underlayer. The CoPt-oxide-based in-plane magnetic film to be formed is a single layer, and no non-magnetic intermediate layer is provided. Specifically, it is as follows.

A Ru underlayer was formed on a Si substrate by sputtering to a thickness of 30 nm, and a CoPt-oxide-based in-plane magnetic film was formed thereon by a sputtering method to a thickness of 30 nm. In this film forming process, the substrate was not heated, and the film was formed at room temperature.

The volume ratio of the oxide (WO ₃ ) of the CoPt-oxide-based in-plane magnetic film to be formed is from 0 vol% to 51.8 vol%, 5.2 vol% or 10.4 vol% (or 10.5 vol%). Samples were prepared by changing the step width, and data were acquired.

The hysteresis loop of the produced CoPt-oxide-based in-plane magnetized film was measured with a vibration magnetometer. Coercive force Hc (kOe) and residual magnetization Mr (memu/cm ³ ) were read from the measured hysteresis loop. Then, the read remanent magnetization Mr (memu/cm ³ ) was multiplied by the film thickness of 30 nm of the manufactured CoPt-oxide system in-plane magnetization film, and the unit area of the manufactured CoPt-oxide system in-plane magnetization film was obtained. Permanent magnetization Mrt (memu/cm ² ) was calculated. The results are shown in Table 2 below.

As can be seen from Table 2, the volume ratio of the oxide (WO ₃ ) to the entire CoPt-oxide-based in-plane magnetization film is 10 to 42 vol%, and the metal component (Co , Pt), the Pt content is 22.5 at%, the thickness is 30 nm, and the coercive force Hc is 2.00 kOe or more, In addition, the magnetic performance that the remanent magnetization Mrt per unit area is 2.00 memu/cm ² or more is realized by film formation at room temperature without heating the substrate.

On the other hand, the volume ratio of the oxide (WO ₃ ) to the entire CoPt-oxide-based in-plane magnetic film is 0 vol %, and Comparative Example 3, which is not within the scope of the present invention, has a coercive force Hc of 1.34 kOe. and the coercive force Hc is less than 2.00 kOe. Further, the volume ratio of the oxide (WO ₃ ) to the entire CoPt-oxide-based in-plane magnetic film is 4.9 vol %, and Comparative Example 4, which is not within the scope of the present invention, has a coercive force Hc of 1. 0.59 kOe and a coercive force Hc of less than 2.00 kOe. Further, the volume ratio of the oxide (WO ₃ ) to the entire CoPt-oxide-based in-plane magnetized film is 46.6 vol %, and Comparative Example 5, which is not within the scope of the present invention, has a residual per unit area of The magnetization Mrt is 1.77 memu/cm ² and the residual magnetization Mrt per unit area is less than 2.00 memu/cm ² . Further, the volume ratio of the oxide (WO ₃ ) to the entire CoPt-oxide-based in-plane magnetized film is 51.8 vol %, and Comparative Example 6, which is not within the scope of the present invention, has a residual per unit area of The magnetization Mrt is 1.53 memu/cm ² and the residual magnetization Mrt per unit area is less than 2.00 memu/cm ² .

<(C) Examination of thickness of in-plane magnetic film of CoPt-oxide system (Examples 9, 12 to 17 and Comparative Examples 7 to 9)>
Experimental data was obtained by changing the thickness of the CoPt-oxide-based in-plane magnetic film (Co-22.5Pt)-20.5 vol% WO ₃ formed on the Ru underlayer. The CoPt-oxide-based in-plane magnetic film (Co-22.5Pt)-20.5vol% WO ₃ to be formed is a single layer, and no non-magnetic intermediate layer is provided. Specifically, it is as follows.

A Ru underlayer was formed on a Si substrate by sputtering to a thickness of 30 nm, and a CoPt-oxide-based in-plane magnetic film (Co- _22.5Pt )-20.5 vol% WO3 was sputtered thereon. Formed by law. In this film forming process, the substrate was not heated, and the film was formed at room temperature.

During sputtering, the sputtering time was changed to change the thickness of the obtained CoPt-oxide-based in-plane magnetic film (Co-22.5Pt) _-20.5vol % WO3 from 10 nm to 100 nm in increments of 10 nm. Samples were prepared and data were acquired.

Here, the thickness of the in-plane magnetic film (Co- _22.5Pt )-20.5vol% WO3 of each sample can be calculated from the sputtering rate and sputtering time. The sputtering rate was calculated by previously measuring the relationship between the thickness of the formed in-plane magnetic film (Co- _22.5Pt )-20.5vol% WO3 and the sputtering time. At this time, the thickness of the in-plane magnetized film (Co- _22.5Pt )-20.5 vol% WO3 was measured using a stylus profilometer (DektakXT manufactured by BRUKER), applying a load of 100 μN to the stylus to determine the thickness of the film adhesion part. The film was passed through the unattached portion, and the height difference in the film thickness direction was obtained and calculated. Furthermore, the vertical cross section of the in-plane magnetized film (Co- _22.5Pt )-20.5vol%WO3 of each sample was observed with a TEM (transmission electron microscope) (Hitachi High-Technologies H-9500) to confirm the film thickness. rice field.

The hysteresis loop of the produced CoPt-oxide-based in-plane magnetized film was measured with a vibration magnetometer. Coercive force Hc (kOe) and residual magnetization Mr (memu/cm ³ ) were read from the measured hysteresis loop. Then, the remanent magnetization Mr (memu/cm ³ ) read was multiplied by the film thickness of the manufactured CoPt-oxide based in-plane magnetized film, and the resulting CoPt-oxide based in-plane magnetized film per unit area The residual magnetization Mrt (memu/cm ² ) was calculated. The results are shown in Table 3 below.

As can be seen from Table ₃ , the thickness of the CoPt-oxide-based in-plane magnetization film (Co-22.5Pt)-20.5 vol% WO3 is 20 to 80 nm. Nos. 12 to 17 realized magnetic properties such as coercive force Hc of 2.00 kOe or more and remanent magnetization Mrt per unit area of 2.00 memu/cm ² or more by room-temperature deposition without substrate heating. ing.

Among Examples 9, 12 to 17, Examples 9, 12, and 13 in which the CoPt-oxide-based in-plane magnetization film (Co-22.5Pt)-20.5 vol% WO ₃ has a thickness of 20 to 40 nm The coercive force Hc is as large as 3.5 kOe or more. Also, the thinner the thickness, the easier it is to apply to the magnetoresistive effect element, and the lower the material cost. Therefore, the thickness of the CoPt-oxide system in-plane magnetic film (Co-22.5Pt)-20.5 vol% WO ₃ is considered to be preferably 20 to 40 nm.

On the other hand, the CoPt-oxide-based in-plane magnetization film (Co- _22.5Pt )-20.5 vol% WO3 has a thickness of 10 nm, and Comparative Example 7, which is not within the scope of the present invention, has a residual per unit area of The magnetization Mrt is 1.26 memu/cm ² and the residual magnetization Mrt per unit area is less than 2.00 memu/cm ² . In addition, the thickness of the CoPt-oxide-based in-plane magnetic film (Co- _22.5Pt )-20.5 vol% WO3 is 90 nm, and Comparative Example 8, which is not within the scope of the present invention, has a coercive force Hc of 1. .78 kOe and a coercive force Hc of less than 2.00 kOe. In Comparative Example 9, in which the thickness of the CoPt-oxide-based in-plane magnetization film (Co- _22.5Pt )-20.5 vol% WO3 is 100 nm, and which is not within the scope of the present invention, the coercive force Hc is 1. .49 kOe and a coercive force Hc of less than 2.00 kOe.

<(D) Examination of types of oxides in CoPt-oxide-based in-plane magnetic films (Examples 10, 18 to 23)>
Experimental data was obtained by variously changing the type of oxide of the CoPt-oxide in-plane magnetic film formed on the Ru underlayer. The CoPt-oxide-based in-plane magnetic film to be formed is a single layer, and no non-magnetic intermediate layer is provided. Specifically, it is as follows.

A Ru underlayer was formed on a Si substrate by sputtering to a thickness of 30 nm, and a CoPt-oxide-based in-plane magnetic film was formed thereon by a sputtering method to a thickness of 30 nm. In this film forming process, the substrate was not heated, and the film was formed at room temperature.

Data were obtained by changing the type of oxide of the CoPt-oxide-based in-plane magnetic film to be formed. _The oxides used _are WO3, _B2O3 , _{MoO3 , Nb2O5 , SiO2} , _Ta2O5 and _TiO2 .

The hysteresis loop of the produced CoPt-oxide-based in-plane magnetized film was measured with a vibration magnetometer. Coercive force Hc (kOe) and residual magnetization Mr (memu/cm ³ ) were read from the measured hysteresis loop. Then, the read remanent magnetization Mr (memu/cm ³ ) was multiplied by the film thickness of 30 nm of the manufactured CoPt-oxide system in-plane magnetization film, and the unit area of the manufactured CoPt-oxide system in-plane magnetization film was obtained. Permanent magnetization Mrt (memu/cm ² ) was calculated. The results are shown in Table 4 below.

As can be seen from Table 4, WO ₃ , B ₂ O ₃ , MoO ₃ , Nb ₂ O ₅ , SiO ₂ , Ta ₂ O ₅ and TiO ₂ were used as the oxides of the CoPt-oxide-based in-plane magnetic film. Examples 10 and 18 to 23 have a composition of (Co-22.5Pt)-30 to 31 vol% oxide and a thickness of 30 nm, and are within the scope of the present invention. The magnetic properties of Hc of 2.00 kOe or more and residual magnetization Mrt of 2.00 memu/cm ² or more per unit area are realized by room-temperature deposition without substrate heating.

In Example 10 using WO ₃ as the oxide and Example 19 using MoO ₃ as the oxide, the coercive force of the produced CoPt-oxide-based in-plane magnetic film exceeded 3 kOe. It is preferable as an oxide used in an oxide-based in-plane magnetic film.

<(E) Investigation of multi-layering of CoPt-oxide-based in-plane magnetic films by non-magnetic intermediate layers (non-magnetic intermediate layers produced using a sputtering target made of metal Ru alone) (Examples 24 to 30) ＞
A non-magnetic intermediate layer (hereafter referred to as metal Ru non-magnetic An intermediate layer is sometimes referred to as an intermediate layer), and the CoPt-oxide-based in-plane magnetization film is multi-layered (two-layered) to obtain experimental data. At that time, the data was obtained by changing the thickness of the metallic Ru non-magnetic intermediate layer provided in the range of 0 nm to 3.0 nm. Specifically, it is as follows.

After forming a Ru underlayer to a thickness of 30 nm on a Si substrate by sputtering, and forming a CoPt-oxide-based in-plane magnetization film thereon by sputtering to a thickness of 30 nm. A metal Ru non-magnetic intermediate layer was formed thereon by sputtering, and a CoPt-oxide based in-plane magnetic film was formed thereon by sputtering to a thickness of 30 nm. In this film formation process, the substrate was not heated, and all film formation was performed at room temperature.

Samples were prepared by changing the thickness of the metal Ru non-magnetic intermediate layer to 0 nm, 0.3 nm, 0.6 nm, 1.2 nm, 1.8 nm, 2.4 nm, and 3.0 nm, and data were obtained.

The hysteresis loop of the produced multilayered sample was measured with a vibrating magnetometer. From the measured hysteresis loop, the coercive force Hc (kOe) of the in-plane magnetized film contained in the multilayered sample and the residual magnetization Mr (memu/cm ³ ) per unit volume were read. Then, by multiplying the total film thickness of 60 nm of the in-plane magnetized films included in the manufactured multilayered sample by the residual magnetization Mr (memu/cm ³ ) per unit volume of the in-plane magnetized films included in the multilayered sample, The residual magnetization Mrt (memu/cm ² ) per unit area of the in-plane magnetized film included in the multilayer sample was calculated. The results are shown in Table 5 below. Note that Example 24 is an example in which no nonmagnetic intermediate layer is provided, and is positioned as a reference example for comparison with Examples 25 to 30 in which a nonmagnetic intermediate layer is provided and the in-plane magnetization film is multi-layered. is an embodiment of

As can be seen from Table 5, in Examples 25 to 30 in which a metal Ru non-magnetic intermediate layer was provided and the in-plane magnetization film was multi-layered, the non-magnetic intermediate layer was not provided and the in-plane magnetization film was a single layer. As compared with Example 24, the coercive force Hc is improved by about 15% or more. On the other hand, the residual magnetization Mrt (memu/cm ² ) per unit area is substantially the same as that of Example 24 (the in-plane magnetization film is a single layer).

Therefore, by multilayering a CoPt-oxide-based in-plane magnetized film with a metal Ru non-magnetic intermediate layer, the coercive force Hc can be reduced to 15 while maintaining the remanent magnetization Mrt (memu/cm ² ) per unit area. % or more.

Further, in Examples 25 to 30 in which a metal Ru nonmagnetic intermediate layer was provided and the in-plane magnetization film was multi-layered, the thickness of the metal Ru nonmagnetic intermediate layer varied in the range of 0.3 to 3.0 nm. However, the coercive force Hc (kOe) and remanent magnetization Mrt per unit area (memu/cm ² ) are almost the same.

Therefore, if the thickness of the metal Ru non-magnetic intermediate layer is in the range of 0.3 to 3.0 nm, the effect (coercive force Hc and remanent magnetization Mrt ) are considered to be equivalent.

<(F) Examination of multi-layering of CoPt-oxide-based in-plane magnetization films by non-magnetic intermediate layers (Ru alloy layers) (Examples 24, 31 to 36)>
A non-magnetic intermediate layer ( Hereinafter, it may be referred to as a Ru alloy non-magnetic intermediate layer), and the CoPt-oxide-based in-plane magnetization film was multi-layered (double-layered) to obtain experimental data. At that time, the data was obtained while changing the thickness of the Ru alloy non-magnetic intermediate layer to be provided in the range of 0 nm to 3.0 nm. Specifically, it is as follows.

After forming a Ru underlayer to a thickness of 30 nm on a Si substrate by sputtering, and forming a CoPt-oxide-based in-plane magnetization film thereon by sputtering to a thickness of 30 nm. A Ru alloy non-magnetic intermediate layer was formed thereon by sputtering, and a CoPt-oxide based in-plane magnetic film was formed thereon by sputtering to a thickness of 30 nm. In this film formation process, the substrate was not heated, and all film formation was performed at room temperature.

Samples were prepared by changing the thickness of the Ru alloy nonmagnetic intermediate layer to 0 nm, 0.3 nm, 0.6 nm, 1.2 nm, 1.8 nm, 2.4 nm, and 3.0 nm, and data were obtained.

The hysteresis loop of the produced multilayered sample was measured with a vibrating magnetometer. From the measured hysteresis loop, the coercive force Hc (kOe) of the in-plane magnetized film contained in the multilayered sample and the residual magnetization Mr (memu/cm ³ ) per unit volume were read. Then, by multiplying the total film thickness of 60 nm of the in-plane magnetized films included in the manufactured multilayered sample by the residual magnetization Mr (memu/cm ³ ) per unit volume of the in-plane magnetized films included in the multilayered sample, The residual magnetization Mrt (memu/cm ² ) per unit area of the in-plane magnetized film included in the multilayer sample was calculated. The results are shown in Table 6 below. Note that Example 24 is an example in which no nonmagnetic intermediate layer is provided, and is positioned as a reference example for comparison with Examples 31 to 36 in which a nonmagnetic intermediate layer is provided and the in-plane magnetization film is multi-layered. is an embodiment of

As can be seen from Table 6, in Examples 31 to 36 in which a Ru alloy nonmagnetic intermediate layer was provided and the in-plane magnetization film was multilayered, the nonmagnetic intermediate layer was not provided and the in-plane magnetization film was a single layer. As compared with Example 24, the coercive force Hc is improved by about 11% or more. On the other hand, the residual magnetization Mrt (memu/cm ² ) per unit area is substantially the same as that of Example 24 (the in-plane magnetization film is a single layer).

Therefore, by multilayering the CoPt-oxide-based in-plane magnetized film with Ru alloy non-magnetic intermediate layers, the coercive force Hc can be reduced to 11 while maintaining the remanent magnetization Mrt (memu/cm ² ) per unit area. % or more.

Further, in Examples 31 to 36 in which the Ru alloy nonmagnetic intermediate layer was provided and the in-plane magnetization film was multi-layered, the thickness of the Ru alloy nonmagnetic intermediate layer varied within the range of 0.3 to 3.0 nm. However, the coercive force Hc (kOe) and remanent magnetization Mrt per unit area (memu/cm ² ) are almost the same.

Therefore, if the thickness of the Ru alloy nonmagnetic intermediate layer is in the range of 0.3 to 3.0 nm, the effect (coercive force Hc and remanent magnetization Mrt ) are considered to be equivalent.

The coercive forces Hc of Examples 25 to 30 in which the nonmagnetic intermediate layer is a metal Ru nonmagnetic intermediate layer and the coercive forces Hc in Examples 31 to 36 in which the nonmagnetic intermediate layer is a Ru alloy nonmagnetic intermediate layer are compared. Although the difference is slight, it can be read from Tables 5 and 6 that the coercive force Hc of Examples 25 to 30, in which the nonmagnetic intermediate layer is a metal Ru nonmagnetic intermediate layer, is larger. As an intermediate layer, a metal Ru non-magnetic intermediate layer is considered more suitable than a Ru alloy non-magnetic intermediate layer.

<(G) Investigation of multi-layering of CoPt-oxide-based in-plane magnetization film by non-magnetic intermediate layer (non-magnetic intermediate layer produced using sputtering target made of metal Cr alone) (Example 24, Comparative example 10-15)>
A non-magnetic intermediate layer (hereafter referred to as metal Cr non-magnetic An intermediate layer is sometimes referred to as an intermediate layer), and the CoPt-oxide-based in-plane magnetization film is multi-layered (two-layered) to obtain experimental data. At that time, data was obtained while changing the thickness of the provided non-magnetic intermediate layer in the range of 0 nm to 3.0 nm. Specifically, it is as follows.

After forming a Ru underlayer to a thickness of 30 nm on a Si substrate by sputtering, and forming a CoPt-oxide-based in-plane magnetization film thereon by sputtering to a thickness of 30 nm. , a metal Cr non-magnetic intermediate layer was formed thereon, and a CoPt-oxide based in-plane magnetization film was formed thereon by a sputtering method to a thickness of 30 nm. In this film forming process, the substrate was not heated, and the film was formed at room temperature.

Samples were prepared by changing the thickness of the metal Cr non-magnetic intermediate layer to 0 nm, 0.3 nm, 0.6 nm, 1.2 nm, 1.8 nm, 2.4 nm, and 3.0 nm, and data were obtained.

The hysteresis loop of the produced multilayered sample was measured with a vibrating magnetometer. From the measured hysteresis loop, the coercive force Hc (kOe) of the in-plane magnetized film contained in the multilayered sample and the residual magnetization Mr (memu/cm ³ ) per unit volume were read. Then, by multiplying the total film thickness of 60 nm of the in-plane magnetized films included in the manufactured multilayered sample by the residual magnetization Mr (memu/cm ³ ) per unit volume of the in-plane magnetized films included in the multilayered sample, The residual magnetization Mrt (memu/cm ² ) per unit area of the in-plane magnetized film included in the multilayer sample was calculated. The results are shown in Table 7 below. Note that Example 24 is an example in which no non-magnetic intermediate layer is provided, and is positioned as a reference example for comparison with Comparative Examples 10 to 15 in which a non-magnetic intermediate layer is provided and the in-plane magnetization film is multi-layered. is an embodiment of

As can be seen from Table 7, in Comparative Examples 10 to 15, in which a metal Cr nonmagnetic intermediate layer was provided and the in-plane magnetization film was multi-layered, the nonmagnetic intermediate layer was not provided and the in-plane magnetization film was a single layer. Compared with Example 24, the coercive force Hc is reduced by 50% or more. On the other hand, the residual magnetization Mrt (memu/cm ² ) per unit area is increased by about 49% or more compared to Example 24 (the in-plane magnetization film is a single layer).

Therefore, by multilayering a CoPt-oxide-based in-plane magnetized film with a metal Cr non-magnetic intermediate layer, the remanent magnetization Mrt (memu/cm ² ) per unit area can be increased by about 49% or more. On the other hand, the coercive force Hc is considered to decrease by 50% or more.

In addition, in Comparative Examples 10 to 15 in which the metal Cr nonmagnetic intermediate layer was provided and the in-plane magnetization film was multi-layered, the thickness of the metal Cr nonmagnetic intermediate layer varied in the range of 0.3 to 3.0 nm. However, the coercive force Hc (kOe) and remanent magnetization Mrt per unit area (memu/cm ² ) are almost the same.

Therefore, if the thickness of the metallic Cr non-magnetic intermediate layer is in the range of 0.3 to 3.0 nm, the effect (coercive force Hc and remanent magnetization Mrt ) are considered to be equivalent.

As described above, when the CoPt-oxide-based in-plane magnetization film is multi-layered with the metal Ru non-magnetic intermediate layer, as shown in Examples 25 to 30, Example 24 (the in-plane magnetization film is a single The coercive force Hc is improved by about 15% or more compared to the non-magnetic intermediate layer), and when the Ru alloy nonmagnetic intermediate layer is multilayered, as shown in Examples 31 to 36, Example 24 (the in-plane magnetized film is a single layer ), the coercive force Hc is improved by about 11% or more. The coercive force Hc is reduced by 50% or more compared to the single layer). The reason for this is that the crystal structure of metal Ru and Ru-25Cr-25Co alloy is a hexagonal close-packed structure hcp, which is the same crystal structure as the magnetic grains (CoPt alloy grains) of the in-plane magnetic film of the CoPt-oxide system. On the other hand, it is considered that the crystal structure of metal Cr is a body-centered cubic structure bcc.

<(H) Investigation of thickness of one in-plane magnetized film in multi-layering of CoPt-oxide-based in-plane magnetized film by non-magnetic intermediate layer (metal Ru single layer) (Examples 24, 37 to 40)>
2.0 nm-thick metal was applied to the positions where the CoPt-oxide in-plane magnetization film formed on the Ru underlayer was divided into 2, 4, 6, and 12 equal parts in the thickness direction. An Ru non-magnetic intermediate layer was provided, and the CoPt-oxide-based in-plane magnetization films were multi-layered so that the total thickness of the CoPt-oxide-based in-plane magnetization films was 60 nm, and experimental data was obtained. bottom. Specifically, it is as follows.

A Ru underlayer was formed on a Si substrate by a sputtering method to a thickness of 30 nm, and a CoPt-oxide-based in-plane magnetic film was formed thereon by a sputtering method to a thickness of 30 nm. After that, a metal Ru nonmagnetic intermediate layer with a thickness of 2.0 nm is formed thereon by sputtering, and a CoPt-oxide-based in-plane magnetic film is formed thereon by sputtering so that the thickness is 30 nm. The total thickness of the CoPt-oxide-based in-plane magnetic film was 60 nm (Example 37).

A Ru underlayer was formed on the Si substrate by sputtering to a thickness of 30 nm, and a CoPt-oxide-based in-plane magnetic film was formed thereon by sputtering to a thickness of 15 nm. After the formation, a metal Ru non-magnetic intermediate layer with a thickness of 2.0 nm is formed thereon by sputtering, and a CoPt-oxide-based in-plane magnetic film is formed thereon by sputtering so as to have a thickness of 15 nm. Then, a metal Ru nonmagnetic intermediate layer with a thickness of 2.0 nm is formed thereon by a sputtering method, and in the same manner until the total thickness of the CoPt-oxide-based in-plane magnetic film reaches 60 nm. By repeating the film formation, a multi-layered sample in which four CoPt-oxide in-plane magnetic films with a thickness of 15 nm were laminated was manufactured (Example 38).

On the Si substrate, a Ru underlayer was formed to a thickness of 30 nm by sputtering, and a CoPt-oxide-based in-plane magnetic film was formed thereon by sputtering to a thickness of 10 nm. After the formation, a metal Ru nonmagnetic intermediate layer with a thickness of 2.0 nm is formed thereon by sputtering, and a CoPt-oxide-based in-plane magnetic film is formed thereon by sputtering so as to have a thickness of 10 nm. Then, a metal Ru nonmagnetic intermediate layer with a thickness of 2.0 nm is formed thereon by a sputtering method, and in the same manner until the total thickness of the CoPt-oxide-based in-plane magnetic film reaches 60 nm. By repeating film formation, a multi-layered sample in which six CoPt-oxide-based in-plane magnetic films with a thickness of 10 nm were laminated was manufactured (Example 39).

On the Si substrate, a Ru underlayer was formed to a thickness of 30 nm by sputtering, and a CoPt-oxide-based in-plane magnetic film was formed thereon by sputtering to a thickness of 5 nm. After the formation, a metal Ru non-magnetic intermediate layer with a thickness of 2.0 nm is formed thereon by sputtering, and a CoPt-oxide-based in-plane magnetic film is formed thereon by sputtering so as to have a thickness of 5 nm. Then, a metal Ru nonmagnetic intermediate layer with a thickness of 2.0 nm is formed thereon by a sputtering method, and in the same manner until the total thickness of the CoPt-oxide-based in-plane magnetic film reaches 60 nm. By repeating the film formation, a multi-layered sample in which 12 in-plane magnetized CoPt-oxide films with a thickness of 5 nm were laminated was manufactured (Example 40).

In these film formation processes, the substrate was not heated, and film formation was carried out at room temperature.

The hysteresis loop of the produced multilayered sample was measured with a vibrating magnetometer. From the measured hysteresis loop, the coercive force Hc (kOe) of the in-plane magnetized film contained in the multilayered sample and the residual magnetization Mr (memu/cm ³ ) per unit volume were read. Then, by multiplying the total film thickness of 60 nm of the in-plane magnetized films included in the manufactured multilayered sample by the residual magnetization Mr (memu/cm ³ ) per unit volume of the in-plane magnetized films included in the multilayered sample, The residual magnetization Mrt (memu/cm ² ) per unit area of the in-plane magnetized film included in the multilayer sample was calculated. The results are shown in Table 8 below. Note that Example 24 is an example in which no nonmagnetic intermediate layer is provided, and is positioned as a reference example for comparison with Examples 37 to 40 in which a nonmagnetic intermediate layer is provided and the in-plane magnetization film is multi-layered. is an embodiment of

As can be seen from Table 8, in Examples 37 to 40 in which a metallic Ru non-magnetic intermediate layer was provided and the in-plane magnetization film was multi-layered, the non-magnetic intermediate layer was not provided and the in-plane magnetization film was a single layer. As compared with Example 24, the coercive force Hc is improved by about 13% or more. On the other hand, the residual magnetization Mrt (memu/cm ² ) per unit area is substantially the same as that of Example 24 (the in-plane magnetization film is a single layer).

Therefore, by multilayering a CoPt-oxide-based in-plane magnetized film with a metal Ru nonmagnetic intermediate layer, the coercive force Hc can be reduced to 13 while maintaining the remanent magnetization Mrt (memu/cm ² ) per unit area. % or more.

In addition, the coercive force Hc of Example 38, which has a four-layer structure in which the thickness of the in-plane magnetization film per layer is 15 nm, is 3.66 kOe. The coercive force Hc is improved by about 55% as compared with Example 24.

Further, the coercive force Hc of Example 39, which has a 6-layer structure with the thickness of the in-plane magnetization film per layer being 10 nm, is 3.04 kOe, and the in-plane magnetization film is a single layer without providing a non-magnetic intermediate layer. The coercive force Hc is improved by about 29% as compared with Example 24.

In addition, the coercive force Hc of Example 37, which has a two-layer structure in which the thickness of the in-plane magnetization film per layer is 30 nm, is 2.76 kOe, and the in-plane magnetization film is a single layer without a non-magnetic intermediate layer. The coercive force Hc is improved by about 17% as compared with Example 24.

Further, the coercive force Hc of Example 40, which has a 12-layer structure in which the thickness of the in-plane magnetization film per layer is 5 nm, is 2.68 kOe. The coercive force Hc is improved by about 14% as compared with Example 24.

Therefore, when the in-plane magnetization film has a plurality of layers, the thickness of each layer is preferably 5 to 30 nm, more preferably 7.5 to 25 nm, and particularly preferably 10 to 20 nm. However, as can be seen from the results of Examples 9, 12 to 17, and Comparative Example 7, when the total thickness (total thickness) of the in-plane magnetized films is less than 20 nm, the remanent magnetization Mrt per unit area decreases by 2. Since it is less than 0.00 memu/cm ² , it is premised that the total thickness of the in-plane magnetic films is 20 nm or more.

<(I) Additional examination of the thickness of one in-plane magnetization film in the multi-layering of the CoPt-oxide in-plane magnetization film by the non-magnetic intermediate layer (metal Ru single layer) and the plane in the in-plane magnetization film multi-layer structure Examination of Total Thickness of Internal Magnetization Film (Examples 41 to 53, Comparative Examples 16 and 17)>
As described in the previous paragraph, when the in-plane magnetization film is formed into multiple layers, the thickness of each layer is preferably 5 to 30 nm, more preferably 7.5 to 25 nm, more preferably 7.5 to 25 nm, from the viewpoint of coercive force Hc. 20 nm is particularly preferred. In order to further investigate this point, an additional study was conducted on the thickness of one layer of the in-plane magnetization film in the multi-layering of the CoPt-oxide-based in-plane magnetization film by the metallic Ru non-magnetic intermediate layer. In addition, in the examination of the in-plane magnetization film multilayer structure in (H) above, only the example in which the total thickness of the in-plane magnetization film was 60 nm was used. A multi-layered structure of the inner magnetization film was also investigated. Further, in the in-plane magnetization film multilayer structure in which the total thickness of the in-plane magnetization film is 100 nm, the content of oxide (WO ₃ ) in the in-plane magnetization film is 31.0 vol % and 10.1 vol %. We considered the case where

As the non-magnetic intermediate layer, a metal Ru non-magnetic intermediate layer having a thickness of 2.0 nm was provided in the same manner as in (H) above, and each in-plane magnetic film multilayer structure was produced. As in the case of (H) above, the substrate was not heated during the film formation process, and the films were all formed at room temperature.

The specific procedure for fabricating each in-plane magnetic film multilayer structure was the same as in (H) above. Measurement of the coercive force Hc (kOe) of the in-plane magnetization film included in the multilayer sample and measurement of the residual magnetization Mrt (memu/cm ² ) per unit area of the in-plane magnetization film included in the multilayer sample were also carried out. It was carried out in the same manner as in (H) above.

The results of these measurements are shown in Tables 9-11 below. Table 9 shows the measurement results when the total thickness of the in-plane magnetization film is ₃₀ nm. Table 11 shows the measurement results when the total thickness of the in-plane magnetization film is 100 nm and the oxide (WO ₃ ) content of the in-plane magnetization film is 10.1 vol%. .

As can be seen from Table 9, in Examples 41 to 43 (the total thickness of the in-plane magnetization films is 30 nm) in which a metallic Ru non-magnetic intermediate layer was provided to form a multi-layered in-plane magnetization film, the non-magnetic intermediate layer was The coercive force Hc is improved by about 3 to 11% as compared with Example 10 in which the in-plane magnetization film is a single layer without any provision. On the other hand, the residual magnetization Mrt per unit area is substantially the same as in Example 10 (the in-plane magnetization film is a single layer).

Therefore, when the thickness of the CoPt-oxide-based in-plane magnetized film is 30 nm, the coercive force Hc can be reduced to 3 while maintaining the remanent magnetization Mrt per unit area by multilayering the metal Ru non-magnetic intermediate layer. It is considered that the improvement can be made by about 11%.

Further, as can be seen from Table 10, Examples 44 to 48 (total thickness of the in-plane magnetized films is 100 nm and oxide (WO ₃ ) content is 31.0 vol%), the coercive force Hc is more than doubled compared to Comparative Example 16 in which the non-magnetic intermediate layer is not provided and the in-plane magnetization film is a single layer. are doing. On the other hand, the remanent magnetization Mrt per unit area is approximately the same as that of Comparative Example 16 (in which the in-plane magnetization film is a single layer), or is at most 12% smaller.

Therefore, when the thickness of the CoPt-oxide system in-plane magnetization film is 100 nm and the oxide (WO ₃ ) content is 31.0 vol %, multi-layering with a metal Ru non-magnetic intermediate layer yields It is believed that the coercive force Hc can be improved by a factor of two or more while maintaining the remanent magnetization Mrt per unit area.

Further, as can be seen from Table 11, Examples 49 to 53 (total thickness of the in-plane magnetized films is 100 nm and oxide (WO ₃ ) content is 10.1 vol%), the coercive force Hc is more than doubled compared to Comparative Example 17 in which the non-magnetic intermediate layer is not provided and the in-plane magnetization film is a single layer. are doing. On the other hand, the residual magnetization Mrt per unit area is approximately the same as that of Comparative Example 17 (in which the in-plane magnetization film is a single layer), or is 12% smaller at maximum.

Therefore, when the thickness of the CoPt-oxide-based in-plane magnetization film is 100 nm and the oxide (WO ₃ ) content is 10.1 vol %, the unit It is believed that the coercive force Hc can be improved by a factor of two or more while the remanent magnetization Mrt per area is substantially maintained.

In addition, Examples 41 to 43, in which the total thickness of the in-plane magnetized films is 30 nm, are all favorable from the viewpoint of improving the coercive force while maintaining the remanent magnetization Mrt (memu/cm ² ) per unit area. Among them, Example 41 (the thickness of one layer of the in-plane magnetization film is 15 nm) and Example 42 (the thickness of one layer of the in-plane magnetization film is 10 nm) are particularly good.

Examples 44-48 with a total in-plane magnetization film thickness of 100 nm and an oxide (WO ₃ ) content of 31.0 vol% maintained remanent magnetization per unit area Mrt (memu/cm ² ). From the viewpoint of improving the coercive force while increasing the coercive force, both are favorable. 12.5 nm in thickness) and Example 47 (the thickness of one layer of the in-plane magnetization film is 10 nm), and Examples 46 and 47 are particularly good.

Examples 49-53 with a ^total thickness of the in-plane magnetized film of 100 nm and an oxide (WO ₃ ) content of 10.1 vol. From the viewpoint of improving the coercive force while increasing the coercive force, both are favorable. 12.5 nm in thickness) and Example 52 (the thickness of one layer of the in-plane magnetization film is 10 nm), and Examples 51 and 52 are particularly good.

Therefore, when the in-plane magnetization film is formed into a plurality of layers described in (H) above, the thickness of each layer is preferably 5 to 30 nm, more preferably 7.5 to 25 nm, from the viewpoint of the coercive force Hc. 10 to 20 nm is particularly preferable” point was also supported by the results of Examples 41 to 53.

Further, from the results of Examples 41 to 43, it was possible to confirm the effect of multilayering the in-plane magnetization films when the total thickness of the in-plane magnetization films was 30 nm. From the results of Examples 44 to 53, it was possible to confirm the effect of multilayering the in-plane magnetization films when the total thickness of the in-plane magnetization films was 100 nm.

<(J) Composition Analysis of In-plane Magnetized Films (Examples 45, 47, 50, 52)>
The composition analysis of the in-plane magnetized films of Examples 45, 47, 50 and 52 was performed. Hereinafter, after explaining the outline of the procedure of the method of the composition analysis performed, the contents of each procedure will be specifically explained.

[Outline of the procedure] Line analysis for composition analysis is performed in the thickness direction of the in-plane magnetized film, and from the locations where the line analysis is performed in the cross-section in the thickness direction of the in-plane magnetized film, locations with little variation in composition are selected (procedure 1-4). Then, a line analysis for composition analysis is performed for a range of 100 nm in the in-plane direction of the in-plane magnetized film (measurement points: 167 points) centering on an arbitrary measurement point included in a location where the composition has little variation ( Step 5). Then, the average value of the detected intensities at 167 measurement points is calculated for each detected element to determine the composition of the in-plane magnetized film (procedure 6). The contents of steps 1 to 6 will be specifically described below.

[Procedure 1] An in-plane magnetized film to be subjected to composition analysis is cut along two parallel planes in a direction perpendicular to the in-plane direction (thickness direction of the in-plane magnetized film), and the obtained two parallel Thinning is performed by the FIB method (μ-sampling method) until the distance between the cut surfaces is about 100 nm. FIG. 3 schematically shows the shape of the thinned sample 80 after the thinning treatment. As shown in FIG. 3, the shape of the sliced sample 80 is generally rectangular parallelepiped. The distance between the two parallel cut surfaces is about 100 nm, and the length of one side in the in-plane direction of the rectangular parallelepiped thinned sample 80 is about 100 nm. If observation by a scanning transmission electron microscope is possible, it may be determined appropriately.

[Procedure 2] The cut surface of the thinned sample 80 obtained in Procedure 1 (the cut surface in the thickness direction of the in-plane magnetized film) can be magnified up to 2 cm with a length of 100 nm (enlarged observation up to 200,000 times Obtain an observation image by imaging using a scanning transmission electron microscope (possible). The observed image obtained is rectangular, and the line at the intersection of the uppermost surface of the in-plane magnetized film to be observed and the cut surface (the cut surface in the thickness direction of the in-plane magnetized film) is the longitudinal direction of the rectangular observed image. Take an image so that it is oriented. An example of the observed image obtained (observed image of Example 45) is shown in FIG. HD-2700 manufactured by Hitachi High-Technologies Corporation was used to obtain an observation image of the in-plane magnetic film.

[Procedure 3] An arbitrary point included in the in-plane magnetized film is selected from the observation image obtained in Procedure 2 (indicated by a black circle 82 in FIG. 4), and a position 10 nm left and right in the longitudinal direction of the observation image from that point. , respectively (indicated by white circles 84 in FIG. 4). Then, line analysis for elemental analysis is performed in the thickness direction of the in-plane magnetized film so as to pass through the points of the black circles 82 , and in the thickness direction of the in-plane magnetized film so as to pass through the points of the white circles 84 . A line analysis was performed for analysis, and three straight lines (one straight line in the thickness direction passing through the points of black circles and two straight lines in the thickness direction passing through the points of white circles) were plotted in the thickness direction of the in-plane magnetized film. line analysis for elemental analysis. When performing the line analysis for this elemental analysis, the scanning range of the line analysis of the three straight lines is the entire range in the thickness direction of the in-plane magnetized film (if the object of composition analysis is the in-plane magnetized film multilayer structure, It is necessary to select one black circle 82 point and two white circle 84 points so that the entire range from the top layer in-plane magnetization film to the bottom layer in-plane magnetization film).

In the composition analysis of the in-plane magnetic film, energy dispersive X-ray analysis (EDX) was adopted as an elemental analysis method, and EMAX Evolution manufactured by Horiba, Ltd. was used as an elemental analysis apparatus. Then, the specific analysis conditions were as follows. That is, the X-ray detector is a Si drift detector, the X-ray extraction angle is 24.8°, the solid angle is about 2.2 sr, a generally appropriate analyzing crystal is used for each element, and the measurement time is 2. Second/point, the scanning point interval was 0.6 nm, and the irradiation beam diameter was about 0.2 nmφ. Hereinafter, the conditions described in this paragraph may be referred to as "analysis conditions of procedure 3".

FIG. 5 shows the result of line analysis (elemental analysis) performed along the black line (the line in the thickness direction of the in-plane magnetized film passing through the dots of the black circles) in FIG. 4 (observed image of Example 45). In FIG. 5, the vertical axis is the detected intensity for each element, and the horizontal axis is the scanning position. Each element shown in the legend in FIG. 5 is an element for which sufficient detection intensity could be confirmed, and in the case of this Example 45, the elements for which sufficient detection intensity could be confirmed are Co, Pt, W, O, Ru Met. In the composition analysis of Example 45, the Kα1 ray was selected for Co and O detection, and the Lα1 ray was selected for Pt, Ru and W detection. Further, each detected intensity was corrected by subtracting the previously measured blank measurement intensity. The final end (bottom end) of the line analysis in FIG. 4 is the Si substrate. Theoretically, only Si and O due to surface oxidation are detected at this location. Therefore, the detected values other than Si and O detected at this point are considered to be unavoidable detection error values in the device. I assumed.

Example 45 has an in-plane magnetization film multilayer structure, and uses a sputtering target with a composition of (Co-20Pt)-30 vol% WO ₃ to form an in-plane magnetization film with a thickness of 25 nm per layer. At the same time, metal Ru non-magnetic intermediate layers were formed between the in-plane magnetized films by 2 nm each so as to be positioned between the in-plane magnetized films. A sputtering target having a composition of 100 at % Ru was used for the deposition of the metal Ru non-magnetic intermediate layer.

As can be seen from the line analysis results shown in FIG. 5, mainly Co, Pt, W and O were confirmed in the in-plane magnetic film, and mainly Ru was confirmed in the non-magnetic intermediate layer. In the metal Ru non-magnetic intermediate layer, the detection intensity based on the constituent elements of the in-plane magnetic film is partially confirmed. This is because However, as far as the distribution of each main element in the in-plane magnetized film and the non-magnetic intermediate layer was observed, it was confirmed that the films were formed roughly as designed.

[Procedure 4] From the results of the line analysis (line analysis performed for elemental analysis in the thickness direction of the in-plane magnetized film) performed in Procedure 3, select a collection point of measurement points with little variation in composition. A collection point of measurement points with little variation in composition is a collection point of measurement points that satisfies the following conditions a to c.

Condition a) A measurement point for any of the three linear line analyzes performed in procedure 3, where the total detected intensity of Co and Pt exceeds 1000 counts.

Condition b) The sum of the detected intensities of Co and Pt at the measurement point is X count, and the next measurement point after the measurement at the measurement point (measurement adjacent to the measurement point at a distance of 0.6 nm below the measurement point) When the sum of the detected intensities of Co and Pt at the point) is taken as Y count,
Y/X−1<0.05
to meet

Condition c) Five or more consecutive measurement points that satisfy conditions a and b.

A collection point of measurement points satisfying the conditions a to c is a continuous measurement point of 5 or more points, and thus becomes a linear area of 0.6 nm×4=2.4 nm or more. Therefore, the gathering point of the measurement points satisfying the conditions a to c is a linear region where at least one of Co and Pt is stably detected in the range of 2.4 nm or more.

[Procedure 5] Select an arbitrary measurement point from the set of measurement points selected in Procedure 4 and use it as a reference point for composition analysis of the in-plane magnetized film (indicated by double white circle 86 in FIG. 4). . Then, with the reference point as the center, a linear region of 50 nm on the left and right in the in-plane direction (longitudinal direction of the observed image in FIG. 4) of the in-plane magnetized film to be subjected to composition analysis (a total linear region of 100 nm, and in FIG. indicated by a white dashed line 88) is subjected to a composition analysis under the same analysis conditions as the analysis conditions in Procedure 3. In this composition analysis, line analysis is performed on a linear region of 100 nm with a scanning point interval of 0.6 nm, so analysis results at a total of 167 measurement points are obtained.

[Procedure 6] Calculate the average value of the detection intensity (number of counts) for the 167 measurement points for each detected element. The ratio of the average values of the detected intensities (number of counts) of each detected element is the composition ratio of each element in the in-plane magnetized film.

In the EDX analysis, it is inevitable that the fluorescent X-rays of light elements such as oxygen (O) are absorbed by the fluorescent X-rays of heavy elements such as platinum (Pt). Light elements such as oxygen (O) and heavy elements such as platinum (Pt) are mixed in the inner magnetization film. Therefore, with respect to oxygen (O), the in-plane magnetization film is assumed to be in an appropriately oxidized state (WO ₃ in Example 45) of all metals present as oxides (W in Example 45). determined the composition of

Further, in Example 18, boron (B) oxide (B ₂ O ₃ ) is used for the in-plane magnetic film. It cannot be detected by analysis in EDX. Therefore, as for the composition of the in-plane magnetic film in Example 18, the composition ratio of Co and Pt can be determined, but the content of B ₂ O ₃ cannot be determined.

The in-plane magnetization film, the in-plane magnetization film multilayer structure, the hard bias layer, the magnetoresistive effect element, and the sputtering target according to the present invention have a coercive force Hc of 2.00 kOe or more and a remanent magnetization Mrt per unit area of A magnetic performance of 2.00 memu/cm ² or more can be achieved without thermal film formation, and has industrial applicability.

DESCRIPTION OF SYMBOLS 10... In-plane magnetic film 12, 24... Magnetoresistive effect element 14, 26... Hard bias layer 16, 28... Free magnetic layer 20... In-plane magnetic film multilayer structure 22... Non-magnetic intermediate layer 50... Insulating layer 52... Pin layer 54 Barrier layer 80 Thinned sample 82 Black circle (an arbitrary point included in the in-plane magnetic film)
84... white circle (points at positions 10 nm left and right in the longitudinal direction of the observed image from the black circle 82)
86... Double white circle (reference point for composition analysis of in-plane magnetic film)
88 … white dashed line (linear region of 50 nm left and right in the longitudinal direction of the observation image from the double white circle 86 (reference point)

Claims (12)

An in-plane magnetized film used as a hard bias layer of a magnetoresistive effect element,
containing metallic Co, metallic Pt and an oxide,
55 at % or more and less than 95 at % of metal Co and more than 5 at % and 45 at % or less of metal Pt with respect to the total metal components of the in-plane magnetization film;
containing 10 vol % or more and 42 vol % or less of the oxide with respect to the entire in-plane magnetized film;
An in-plane magnetic film having a thickness of 20 nm or more and 80 nm or less. 2. An in-plane magnetized film according to claim 1, having a granular structure consisting of CoPt alloy crystal grains and crystal grain boundaries of said oxide. 3. The in-plane magnetization film according to claim 1, wherein said oxide contains at least one of oxides of Ti, Si, W, B, Mo, Ta and Nb. An in-plane magnetic film multilayer structure used as a hard bias layer of a magnetoresistive effect element,
a plurality of in-plane magnetized films;
a non-magnetic intermediate layer;
and
the non-magnetic intermediate layer is arranged between the in-plane magnetized films, and the in-plane magnetized films adjacent to each other with the non-magnetic intermediate layer interposed therebetween are ferromagnetically coupled to each other;
The in-plane magnetization film is
containing metallic Co, metallic Pt and an oxide,
55 at % or more and less than 95 at % of metal Co and more than 5 at % and 45 at % or less of metal Pt with respect to the total metal components of the in-plane magnetization film;
The in-plane magnetization film contains 10 vol % or more and 42 vol % or less of the oxide,
The in-plane magnetization film multilayer structure has a coercive force of 2.00 kOe or more and a residual magnetization per unit area of 2.00 memu/cm ² or more. An in-plane magnetic film multilayer structure used as a hard bias layer of a magnetoresistive effect element,
a plurality of in-plane magnetized films;
a non-magnetic intermediate layer having a hexagonal close-packed crystal structure;
and
the non-magnetic intermediate layer is arranged between the in-plane magnetized films, and the in-plane magnetized films adjacent to each other with the non-magnetic intermediate layer interposed therebetween are ferromagnetically coupled to each other;
The in-plane magnetization film is
containing metallic Co, metallic Pt and an oxide,
55 at % or more and less than 95 at % of metal Co and more than 5 at % and 45 at % or less of metal Pt with respect to the total metal components of the in-plane magnetization film;
10 vol % or more and 42 vol % or less of the oxide with respect to the entire in-plane magnetized film,
The in-plane magnetization film multilayer structure, wherein the total thickness of the plurality of in-plane magnetization films is 20 nm or more. 6. The in-plane magnetic film multilayer structure according to claim 4, wherein said non-magnetic intermediate layer is made of Ru or Ru alloy. 7. The in-plane magnetization film multilayer according to claim 4, wherein said in-plane magnetization film has a granular structure consisting of CoPt alloy crystal grains and crystal grain boundaries of said oxide. structure. 8. The in-plane magnetic film multilayer according to any one of claims 4 to 7, wherein said oxide includes at least one of oxides of Ti, Si, W, B, Mo, Ta and Nb. structure. 9. The in-plane magnetization film multilayer structure according to claim 4, wherein the thickness of each layer of the in-plane magnetization film is 5 nm or more and 30 nm or less. A hard bias layer comprising the in-plane magnetization film according to any one of claims 1 to 3 or the in-plane magnetization film multilayer structure according to any one of claims 4 to 9. A magnetoresistive element comprising the hard bias layer according to claim 10 . A sputtering target used when forming an in-plane magnetized film used as at least a part of a hard bias layer of a magnetoresistance effect element at room temperature,
containing metallic Co, metallic Pt and an oxide,
Containing 60 at% or more and less than 95 at% of metal Co and more than 5 at% and 40 at% or less of metal Pt with respect to the total metal components of the sputtering target,
Containing 10 vol% or more and 40 vol% or less of the oxide with respect to the entire sputtering target,
A sputtering target, wherein the in-plane magnetization film to be formed has a coercive force of 2.00 kOe or more and a residual magnetization of 2.00 memu/cm ² or more per unit area.

Images